What is Intracranial Hypotension?
Intracranial hypotension is a condition in which there is abnormally low pressure or volume within the skull due to a reduction in cerebrospinal fluid (CSF).
Cerebrospinal fluid is the colorless fluid that surrounds the brain and spinal cord. It is continuously produced in the cavities of the brain called ventricles and absorbed into the bloodstream. This fluid cushions the brain and acts as a shock absorber. It also serves as a vehicle for delivering nutrients to and removing waste from the brain.
When the volume of cerebrospinal fluid is reduced—often due to a CSF leak—the normally floating brain sags within the skull. This results in a headache and other neurological symptoms.
Symptoms of Intracranial Hypotension
Symptoms of intracranial hypotension include:
- Positional headache, which worsens when you sit up and improves when you lie down
- Sensitivity to light or sound
- Nausea, with or without vomiting
- Neck pain or stiffness
- Hearing changes, such as muffled hearing or ringing in the ears
- Difficulty concentrating
- Double vision
- Memory impairment
Many medical conditions can cause headaches accompanied by other neurological symptoms. Contact a medical professional if you are having symptoms.
Treatments for Intracranial Hypotension
Depending on the cause of the cerebrospinal fluid leak, symptoms may resolve on their own. Your doctor may initially recommend bed rest, drinking more fluids, increasing your caffeine intake, and taking pain relievers.
If your symptoms do not improve with conservative treatments, your doctor may suggest an epidural blood patch. This procedure involves taking blood from the arm and injecting it into the spinal canal outside of the dura to seal the leak. It is performed by a neuroradiologst under video X-ray guidance.
If you have intracranial hypotension due to the over-draining of a shunt system, you may need to have the valve on the shunt replaced.
How common is intracranial hypotension?
Intracranial hypotension affects an estimated 5 per 100,000 people, but it is thought to be underdiagnosed.
Who gets intracranial hypotension?
Intracranial hypotension affects men, women, and children of all ages. However, it is more common in women than in men, and the peak age of diagnosis is 40.
Intracranial hypotension often results from a cerebrospinal fluid leak. CSF leaks can occur without an identifiable cause, or they can be caused by:
- Lumbar puncture (spinal tap)
- Placement of tubes for epidural anesthesia or pain medications
- Spinal trauma
- Spinal surgery
Underlying weakness of the spinal dura, the outermost layer of the protective tissues surrounding the brain and spinal cord, is present in many cases of spontaneous intracranial hypotension. Several genetic disorders have been associated with areas of thin or weak dura that may predispose people to CSF leaks. These include:
- Ehlers-Danlos syndrome
- Marfan syndrome
- Autosomal dominant polycystic kidney disease
Over-drainage of a shunt system placed for hydrocephalus can also cause intracranial hypotension.
How is intracranial hypotension diagnosed?
Your doctor may use the following to diagnose intracranial hypotension:
- Physical and neurological examinations
- Magnetic Resonance Imaging (MRI) with contrast
- MR, digital subtraction, and CT myelography may be used to locate the site of the leak